Cedar River IA 02-CED-468

from dam of Cedar Falls Impoundment (NW 1/4 S12 T89N R14W Black Hawk Co.) to upper end of impoundment (W line S2 T89N R14W Black Hawk Co.)

Open Data Collection Period Modal

For purposes of developing stream/river water quality assessments for integrated reporting, three years of water quality data are typically used for both conventional pollutant parameters (e.g., indicator bacteria) and the less frequently monitored toxic parameters (e.g., toxic metals). Since the 2004 IR cycle, DNR has used a three-year data gathering period for streams, rivers, and beaches. For most assessments, the use of three years of data increases the number of samples upon which the decision on use support is based and helps address the problem of weather-related year-to-year fluctuations in water quality.

Due to the lower sampling frequency in Iowa’s ambient lake, biological, fish kill, and fish tissue monitoring programs, five years of data are used for developing IR assessments and for identifying Section 303(d) listings.

Data Type	Data Timeframe
Beach Sampling Data	CY 2018 - 2020
Stream/River Water Quality Data	CY 2018 - 2020
Lake Water Quality Data	CY 2016 - 2020
Biological Sampling Data	CY 2016 - 2020*
Fish Kill Data	CY 2016 - 2020
Fish Tissue Sampling Data	CY 2016 - 2020
Continuous Dissolved Oxygen Sampling Data	CY 2016 - 2020
*Biological sites sampled in both 2015 and 2019 were also assessed.

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Cycle: 2022
Release Status: Final
Overall IR: 4 - Water is impaired or threatened and a TMDL has been completed or is not needed.
Trend: Unknown
Created: 12/16/2021 8:29:51 AM
Updated: 12/16/2021 8:33:41 AM

Use Support

Class A1

Recreation - Primary contact

Not Supported

Bacteria: Indicator Bacteria- E. coli

Support Level

Not Supported

Impairment Code

4a - Pollutant-caused impairment. TMDL has been completed.

Cause Magnitude

Slight

Status

Continuing

Source

Unknown: Source Unknown

Source Confidence

N/A

Cycle Added

2004

Impairment Rationale

Significantly > 10% of samples fail to meet criterion

Data Source

Ambient monitoring: Iowa DNR-rivers

Class BWW1

Aquatic Life - Warm Water Type 1

Fully Supported

Class HH

Human Health -

Not Assessed

Impairment Delistings

No delistings for this assessment cycle.

Documentation

Assessment Summary

The Class A1 use was assessed as "not supported" based on levels of indicator bacteria that violated state water quality criteria. The Class BWW1 use was assessed as "fully supported" based on biological sampling data and water quality monitoring data. All other designated uses were "not assessed." Note: A TMDL for the bacteria impairment in this segment of Cedar River was prepared and was approved by EPA in February 2010. The bacteria impairment of the Class A1 primary contact recreation use for this segment was moved to IR Category 4a (TMDL prepared and approved).

Assessment Explanation

Data Sources:

Data Source	Data Source ID	Data Type	Data Age	Site ID	Site Name	Site Description
Iowa DNR	6	WQ	CY 2012-2014	10070005	Cedar River upstream of Waterloo/Cedar Falls
Iowa DNR	6	BIO	See Below	1197	Cedar River	Cedar Falls – REMAP #432
Iowa DNR	6	BIO	See Below	950	Cedar River	Waterloo – US1

Class A1 – Indicator Bacteria: 2012-2014

Site ID	Data Source ID	# Samples / # Years	2012 Geometric Mean	2013 Geometric Mean	2014 Geometric Mean	Annual Geometric Mean Violation	# Violations	% Violations	Significantly >10% Violations	Assessment Type	Support Level
10070005	6	22 / 3	26	99	58	No	5	21%	Yes	Evaluated	Not

Class A1 - pH: 2012-2014

Site ID	Data Source ID	# Samples / # Years	Maximum Value	Mean Value	Median Value	# Violations	% Violations	Significantly >10% Violations	Assessment Type	Support Level
10070005	6	33 / 3	9.1	8.22	8.2	1	3%	No	Evaluated	Full

Class BWW1 - Conventional Parameters: 2012-2014

Site ID	Data Source ID	Parameter Name	# Samples / # Years	Maximum Value	Mean Value	Median Value	# Acute / Chronic Violations	% Acute/ Chronic Violations	Significantly >10% Violations	Assessment Type	Support Level
10070005	6	Ammonia	33 / 3	0.48	0.09	0.05	0 / 0	0% / 0%	No	Evaluated	Full
10070005	6	Chloride	33 / 3	47	23.8	23	0 / 0	0% / 0%	No	Evaluated	Full
10070005	6	Dissolved oxygen	33 / 3	17.7	11.3	11.1	NA / 0	NA / 0%	No	Evaluated	Full
10070005	6	pH	33 / 3	9.1	8.22	8.2	1 / NA	3% / NA	No	Evaluated	Full
10070005	6	Sulfate	33 / 3	42	29.7	31	0 / NA	0% / NA	No	Evaluated	Full
10070005	6	Temperature	33 / 3	28.5	11.7	10.5	0 / 0	0% / 0%	No	Evaluated	Full

Class BWW1 - Biological Sampling:

Benthic Macroinvertebrates:

Site ID	Date	Drainage Area (mi2)	Ecoregion	Major Drainage	BM Sample Gear	BMIBI score	BMIBI Class	47c BMIBI BIT	BMIBI Pass/Fail
1197	8/21/19	4720	47c	MS	Floating Art Sub	66	Good	52	Pass
950	9/9/14	4734	47c	MS	Hess	62	Good	70	Fail
950	9/9/14	4734	47c	MS	Floating Art Sub	63	Good	52	Pass

Fish:

Site ID	Date	Drainage Area (mi2)	Ecoregion	Major Drainage	Riffle Stream?	FIBI score	FIBI Class	47c FIBI BIT	FIBI Pass/Fail
1197	8/21/19	4720	47c	MS	Undetermined	50	Fair	44	Pass

Overall:

Community	Assessment Type	Assessment Result	Support Level	IR Category	Reason
Benthic Macroinvertebrates	Evaluated	Pass (2/3)	Full
Fish	Evaluated	Pass (1/1)	Full	1	Assessment was evaluated because the drainage areas of the sample sites
Overall	Evaluated	Pass	Full		were greater than the calibrated range.

Class HH – No Data

Monitoring and Methods

Assessment Key Dates

1/5/2012

Fixed Monitoring Start Date

9/9/2014

Fixed Monitoring End Date

8/21/2019

Biological Monitoring

9/9/2014

Biological Monitoring

2/26/2010

TMDL Completed

Methods

150

Monitoring data more than 5 years old

230

Fixed station physical/chemical (conventional plus toxic pollutants)

315

Regional reference site approach

320

Benthic macroinvertebrate surveys

330

Fish surveys

420

Indicator bacteria monitoring